Cylindrical Morphology Research Articles

Capsaicin-incorporated zein electrospun nanofibers: Characterization and release behavior

Capsaicin is an active compound in hot chili pepper that possesses many beneficial biological properties. However, sensorial attributes and sensitivity to environmental and food processing conditions can affect their stability, which could be restricted by encapsulation. In this study, electrospun zein fibers loaded with different concentrations of capsaicin (0.1%–0.4%) were evaluated in terms of encapsulation efficiency, morphology, and antioxidant activity. Nano-sized fibers were obtained with an encapsulation efficiency of 45.73%–93.11%, exhibiting a smooth surface and cylindrical morphology. The capsaicin-loaded zein fibers showed antioxidant activity in the range of 60%–68%. An optimum concentration of 0.24% capsaicin was selected for zein nanofibers. The release from the zein nanostructure in the food simulants followed Fickian transport. The interactions of capsaicin with zein were characterized by frequency shifts of the complex spectra. Thermogravimetric and thermal stability tests showed that capsaicin loss decreased following encapsulation in the electrospun zein mat. The thermal stability of encapsulated capsaicin increased more than 50% at 90 °C in comparison with free capsaicin. The nanofibers showed higher antimicrobial activity against Staphylococcus aureus than Pseudomonas aeruginosa and then Escherichia coli. Overall, zein acted as a good wall material for the encapsulation of capsaicin via electrospinning, extending the applications of capsaicin in foods and therapeutics.

Electro-Catalytic Properties of Palladium and Palladium Alloy Electro-Catalysts Supported on Carbon Nanofibers for Electro-Oxidation of Methanol and Ethanol in Alkaline Medium

Carbon nanofibers (CNFs) supported by Pd and Pd-Sn electro-catalysts were prepared by the chemical reduction method using ethylene glycol as the reducing agent. Their physicochemical characteristics were studied using high resolution-transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Bruanaer-Emmett-Teller (BET) analysis. FTIR revealed that oxygen, hydroxyl, carboxylic and carbonyl functional groups facilitated the dispersion of Pd and Sn nanoparticles. The doping of Pd with Sn to generate PdSn alloy was also confirmed by XPS data. The amorphous nature of CNFs was confirmed by XRD patterns which exhibited the Pd diffraction peaks. When Sn was added to Pd/CNFs, the diffraction peaks moved to lower angles. HRTEM images revealed that the CNFs with cylindrical shape-like morphology and also Pd-Sn nanoparticles dispersed on carbon support. The catalytic activity and stability towards alcohol electro-oxidation in alkaline medium at room temperature was evaluated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The obtained Pd-Sn/CNFs electro-catalyst exhibited a better electro-catalytic activity than Pd/CNFs and Pd/C electro-catalysts for both methanol and ethanol oxidation. The improvement of the electrochemical performance was associated with the synergistic effect via the addition of Sn which modified the Pd atom arrangement, thereby promoting oxidation through a dehydrogenation pathway. Furthermore, SnO2 generates abundant OH species which helps with increasing the rate of the oxidative removal of carbon monoxide (CO) intermediates from Pd sites.

Discrete, Shallow Doping of Semiconductors via Cylinder‐Forming Block Copolymer Self‐Assembly

AbstractBlock copolymer (BCP) self‐assembly‐assisted doping for semiconductors is used to achieve discrete doping with nanometer‐scale junction depth, high throughput, and large area coverage. As devices become smaller and more sophisticated, spatial control of dopants becomes more critical. A variety of doping methods, such as monolayer doping and δ‐doping, have been developed to replace the conventional doping method, ion‐implantation; however, lateral patterning of dopants relies on photo‐ or e‐beam lithography. To address these challenges, a self‐assembling dopant (boron)‐containing BCP is designed to directly pattern dopants on the nanometer scale. This method skips the lithography step and is compatible with directed self‐assembly approaches. The effect of the boron concentration in the BCP on the doping performance is systematically studied by changing the volume fraction of the boron‐containing block while keeping the domain spacing and the mesoscale morphology constant. Successful self‐assembly of the BCP into a hexagonally packed cylindrical morphology is confirmed by small‐angle X‐ray scattering and resonant soft X‐ray scattering with a 26 nm cylinder‐to‐cylinder distance. Doping silicon using these BCPs enables discrete doped areas with shallow (7–13 nm) junction depth as demonstrated by the depth profile of boron, and supported by a sheet resistance study.

MOF‐Derived Cu/Bi Bi‐metallic Catalyst to Enhance Selectivity Toward Formate for CO2 Electroreduction

AbstractConverting CO2 into high‐value liquid products is a promising strategy to alleviate energy crisis. Herein, a novel Cu/Bi bi‐metal catalyst derived from MOFs has been prepared by a hydrothermal synthesis combining with high temperature calcination under N2 atmosphere, which shows cylindrical morphology composed of bi‐metallic nanoparticles. It is found that Cu/Bi bi‐metallic system is beneficial to lower the activate energy barrier of CO2 and shows a stronger adsorption capability for the CO2 ⋅ − intermediate than that of reference Bi/Bi2O3@C without Cu species. XPS analysis indicates the boosted performance for CO2 reduction reaction, which could be ascribed to synergistic coordination of Bi0 and Bi3+ in the catalyst. The optimized Cu1−Bi/Bi2O3@C exhibits excellent selectivity toward HCOOH with faradaic efficiency (FE) exceeding 84 % between −0.84 and −1.14 V vs. RHE, and even reaching 93 % at −0.94 V vs. RHE. The obtained Cu/Bi bi‐metal catalyst shows a promising application prospect in the CO2 reduction.

The nasopalatine canal and its relationship with the maxillary central incisors: a cone-beam computed tomography study

Objective: To evaluate the dimensions of the nasopalatine canal (NPC) and its relationship with the maxillary central incisors (MCI) using cone-beam computed tomography (CBCT) and to determine variations in the NPC in relation to age and gender. Methods: CBCT scans from 333 patients (67% female; 35.9 ± 14.6 years) were included. The CBCT scan was analyzed to determine the length and diameter of the NPC, the distance between the NPC and the MCI, and to evaluate the morphology of the NPC. The data were analyzed using the independent Student's t-test, the Mann–Whitney and Kruskal–Wallis tests, and Dunn's post-test (p < 0.05). Results: The average diameter and length of the NPC were 2.92 ± 0.91 mm and 12.67 ± 3.32 mm, respectively. The minimum and maximum distance between the MCI and the NPC were 0.78 ± 0.42 mm and 2.56 ± 1.38 mm, respectively. The NPC of male patients was greater in length compared with the female patients (p < 0.05). The majority presented a funnel-like morphology (34.1%), followed by a cylindrical morphology (27.5%). Conclusions: There was variability in the dimensions of the NPC and its relationship with the MCI, which was influenced by gender and age.

Research on the influence of Micro-morphology on the hydrophobicity of material surface

In this study, numerical simulation and physical experiments are carried out to investigate the influence of material surface microstructure on its hydrophobicity. By observing the contact angle and liquid phase state of the droplet on various morphological surfaces, the relationship between the size and morphology of microstructures and the hydrophobicity of material surface is explored. The influence of microstructure on the hydrophobicity is reflected by:1. changes of the contact angle along with the changes of microstructure size, 2. anisotropy of liquid droplet spreading along with the changes of wire groove and cylindrical morphology. Driven by tension, droplets can move spontaneously on the surface of specific microstructures, and the moving speed and direction vary with the distribution of the microstructures.

Smart and pH-sensitive rGO/Arabinoxylan/chitosan composite for wound dressing: In-vitro drug delivery, antibacterial activity, and biological activities

Carbohydrate polymers are biological macromolecules that have sparked a lot of interest in wound healing due to their outstanding antibacterial properties and sustained drug release. Arabinoxylan (ARX), Chitosan (CS), and reduced graphene oxide (rGO) sheets were combined and crosslinked using tetraethyl orthosilicate (TEOS) as a crosslinker to fabricate composite hydrogels and assess their potential in wound dressing for skin wound healing. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and biological assays were used to evaluate the composite hydrogels. FTIR validated the effective fabrication of the composite hydrogels. The rough morphologies of the composite hydrogels were revealed by SEM and AFM (as evident from the Ra values). ATC-4 was discovered to have the roughest surface. TEM revealed strong homogeneous anchoring of the rGO to the polymer matrix. However, with higher amount of rGO agglomeration was detected. The % swelling at various pHs (1−13) revealed that the hydrogels were pH-sensitive. The controlled release profile for the antibacterial drug (Silver sulfadiazine) evaluated at various pH values (4.5, 6.8, and 7.4) in PBS solution and 37 °C using the Franz diffusion method revealed maximal drug release at pH 7.4 and 37 °C. The antibacterial efficacy of the composite hydrogels against pathogens that cause serious skin diseases varied. The MC3T3-E1 cell adhered, proliferated, and differentiated well on the composite hydrogels. MC3T3-E1 cell also illustrated excellent viability (91%) and proper cylindrical morphologies on the composite hydrogels. Hence, the composite hydrogels based on ARX, CS, and rGO are promising biomaterials for treating and caring for skin wounds.

A facile method of generating aluminosilicate nanoparticles: Complete fragmentation of kaolinite nanoscrolls via manual grinding

Aluminosilicate nanoparticles were prepared by the complete breakdown of the tube walls of kaolinite nanoscrolls by manual grinding. Transmission electron microscopy observation of the product showed a lack of the original hollow cylindrical morphology together with the formation of nanoparticles Hysteresis over the relative pressure range of 0.50–0.95 was present in the nitrogen adsorption/desorption isotherm of kaolinite nanoscroll but not in that of ground product. These results indicate the successful formation of kaolinite nanoparticles using a simple grinding method.

Electrospun PVP-Core/PHBV-Shell Fibers to Eliminate Tailing Off for an Improved Sustained Release of Curcumin.

Tailing off release in the sustained release of water-insoluble curcumin (Cur) is a significant challenge in the drug delivery system. As a novel solution, core-shell nanodrug containers have aroused many interests due to their potential improvement in drug-sustained release. In this work, a biodegradable polymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and hydrophilic polyvinylpyrrolidone (PVP) were exploited as drug delivery carriers by coaxial electrospinning, and the core-shell drug-loaded fibers exhibited improved sustained release of Cur. A cylindrical morphology and a clear core-shell structure were observed by scanning and transmission electron microscopies. The X-ray diffraction pattern and infrared spectroscopy revealed that Cur existed in amorphous form due to its good compatibility with PHBV and PVP. The in vitro drug release curves confirmed that the core-shell container manipulated Cur in a faster drug release process than that in the traditional PHBV monolithic container. The combination of the material and structure forms a novel nanodrug container with a better sustained release of water-insoluble Cur. This strategy is beneficial for exploiting more functional biomedical materials to improve the drug release behavior.

Mesoporous silicas of MCM-41 type modified with iron species by template ion-exchange method as catalysts for the high-temperature NH3-SCR process – Role of iron species aggregation, silica morphology and associated reactions

Mesoporous silica of MCM-41 type with cylindrical and spherical morphology was synthesized and modified with iron species by template ion-exchange (TIE) method. Methanol solutions of FeCl2 and [Fe3(OCOCH3)7·OH·2 H2O]NO3, used as iron precursors, resulted in deposition of this metal in highly dispersed and aggregated forms, respectively. The obtained samples were characterized with respect to chemical composition - iron loading and surfactant content in non-calcined silicas (ICP-OES, TG-DSC), texture (low-temperature N2 sorption, XRD), morphology (SEM-EDS), form and aggregation of deposited iron species (UV–vis DRS, XRD, SEM-EDS), surface acidity (NH3-TPD) and reducibility of deposited iron species (H2-TPR). Iron modified silicas presented a very good catalytic performance in the high-temperature NH3-SCR process (effective operation in the range of 350–475 °C), however the specific catalytic activity depends on the morphology of the silica samples as well as the form and aggregation of deposited iron species. Moreover, the reactions associated with the NH3-SCR process, such as NO to NO2 oxidation and direct ammonia oxidation were studied.

Expanding Alternating Spherical and Cylindrical Regions by Tailoring Binary Symmetric ABC/ABC Blends

The self-assembly of a binary blend composed of two different symmetric ABC triblock copolymers has been investigated using self-consistent field theory in the grand canonical ensemble, aiming to expand the phase regions of alternating spherical and cylindrical phases by tailoring the molecular parameters. Our study confirms that the region of the spherical phase is expanded by the effect of bidispersity in which the long and short A-blocks (or C-blocks) form a core–shell distribution within the spherical domain to increase the spontaneous curvature. The bidispersity effect also expands the phase region of the alternating cylinders. In contrast to the spherical phase, the cylindrical region can be expanded by another effect of bidisperse B-blocks to release the high packing frustration of the low-coordinated tetragonal array of alternating A/C cylinders. With optimized parameters, the regions of both the spherical and cylindrical phases are tremendously expanded to such large volume fractions that the spheres and cylinders are remarkably deformed. Our work not only deepens the understanding on the self-assembly mechanism of ABC/ABC blends but also provides a valuable guide for the fabrication of alternating spherical and cylindrical morphologies with large volume fractions.

Myoblast mechanotransduction and myotube morphology is dependent on BAG3 regulation of YAP and TAZ

Skeletal muscle tissue is mechanically dynamic with changes in stiffness influencing function, maintenance, and regeneration. We modeled skeletal muscle mechanical changes in culture with dynamically stiffening hydrogels demonstrating that the chaperone protein BAG3 transduces matrix stiffness by redistributing YAP and TAZ subcellular localization in muscle progenitor cells. BAG3 depletion increases cytoplasmic retention of YAP and TAZ, desensitizing myoblasts to changes in hydrogel elastic moduli. Upon differentiation, muscle progenitors depleted of BAG3 formed enlarged, round myotubes lacking the typical cylindrical morphology. The aberrant morphology is dependent on YAP/TAZ signaling, which was sequestered in the cytoplasm in BAG3-depleted myotubes but predominately nuclear in cylindrical myotubes of control cells. Control progenitor cells induced to differentiate on soft (E’ = 4 and 12 kPa) hydrogels formed circular myotubes similar to those observed in BAG3-depleted cells. Inhibition of the Hippo pathway partially restored myotube morphologies, permitting nuclear translocation of YAP and TAZ in BAG3-depleted myogenic progenitors. Thus, BAG3 is a critical mediator of dynamic stiffness changes in muscle tissue, coupling mechanical alterations to intracellular signals and inducing changes in gene expression that influence muscle progenitor cell morphology and differentiation.

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block.

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

Size and Shape Control of Ice Crystals by Amphiphilic Block Copolymers and Their Implication in the Cryoprotection of Mesenchymal Stem Cells.

Precise control over the size and shape of ice crystals is a key factor to consider in designing antifreezing and cryoprotecting molecules for cryopreservation of cells. Here, we report that a poly(ethylene glycol)-poly(l-alanine) (PEG-PA) block copolymer exhibits excellent cryoprotecting properties for stem cells and antifreezing properties for water. As the molecular weight of PA increased from 500, 760, and 1750 Da (P1, P2, and P3) at the same PEG molecular weight of 5000 Da, the β-sheet content decreased and α-helix content increased. Comparing P2 (PEG-PA; 5000-760) and P4 (PEG-PA: 1000-750), β-sheets increased as the PEG block length decreased. The critical micelle concentration of the PEG-PA block copolymers was in a range of 0.5-3.0 mg/mL and was proportional to the hydrophobicity of the PEG-PA block copolymers. The P1, P2, and P3 self-assembled into spherical micelles, whereas P4 formed micelles with cylindrical morphology. The difference in the block copolymer structure affected ice recrystallization inhibition (IRI) activity and cryopreservation of cells. IRI activity was assayed via mean largest grain size (MLGS), and interactions between polymers and ice crystal surfaces were studied by dynamic ice-shaping studies. The MLGS decreased to 58 → 53 → 45 → 35 → 23% of that of PBS, as the polymer (PEG-PA 5000-500) concentration increased from 0.0 (PBS; control) → 1.0 → 5.0 → 10 → 30 → 50 mg/mL. The MLGS of PEG 5k solutions (negative control) decreased to 74 → 71 → 64 → 44 → 37% of that of PBS in the same concentration range. P3 and P4 with a longer hydrophobic PA block developed elongated ice crystals at above 30 mg/mL. The dynamic ice-shaping study exhibited that ice crystals became needle-shaped, as the hydrophobicity of the polymer increased as in P2-P4. The cell recovery in the P1 system after cryopreservation at -196 °C for 7 days was 87% of that of the dimethyl sulfoxide (DMSO) 10% system (positive control). The cell recovery was 48% for the P2 system and drastically decreased to less than 30% of that of the DMSO 10% system in the P3, P4, PEG 5k, PEG 1k, PVA 80H, and PVA 100H systems. Current studies suggest that IRI activity, round ice crystal shaping, and membrane stabilization activity of P1 cooperatively provide excellent cell recovery among the candidate systems. Recovered stem cells exhibited excellent proliferation and multilineage differentiation into osteocytes, chondrocytes, and adipocytes. To conclude, the PEG-PA (5000-500) block copolymer is suggested to be a promising antifreezing cryoprotectant for stem cells.

Preparation and distorted cylindrical morphology of block copolymers consisting of flexible and semiflexible blocks

Preparation and distorted cylindrical morphology of block copolymers consisting of flexible and semiflexible blocks

Structure/Properties Relationship of Anionically Synthesized Diblock Copolymers "Grafted to" Chemically Modified Graphene.

A novel approach to obtaining nanocomposite materials using anionic sequential polymerization and post-synthetic esterification reactions with chemically modified graphene sheets (CMGs) is reported. The anionically synthesized diblock copolymer precursors of the PS-b-PI-OH type were grafted to the chemically modified –COOH groups of the CMGs, giving rise to the final composite materials, namely polystyrene-b-poly(isoprene)-g-CMGs, which exhibited enhanced physicochemical properties. The successful synthesis was determined through multiple molecular characterization techniques together with thermogravimetric analysis for the verification of increased thermal stability, and the structure/properties relationship was justified through transmission electron microscopy. Furthermore, the arrangement of CMGs utilizing lamellar and cylindrical morphologies was studied in order to determine the effect of the loaded CMGs in the adopted topologies.

Cochleate Formulation Enhances the Stability of Lansoprazole in Acidic Condition

Lansoprazole (LSP)‐loaded cochleates were developed using dimyristoyl phosphatidylcholine (DMPC) and cholesterol in the presence or absence of dicetyl phosphate (DCP). Cochleates containing DCP exhibited unique cylindrical morphologies, resulting in improved LSP loading and enhanced stability in an acidic environment. Thus, we suggest that the use of negatively charged components, such as DCP, is needed to formulate cochleates using a neutrally charged lipid such as DMPC.

Three-dimensional macroassembly of chromic hydroxide

Assembly of small building blocks such as atoms, molecules, nanoparticles, and microparticles into macroscopic structures has opened up new and exciting opportunities in the realm of nanotechnology and microtechnology. Here, we report a simple hydrothermal approach for assembling chromic hydroxide microscopic particles into three-dimensional chromic hydroxide with cylindrical morphology. The morphology and size as prepared samples are controlled by the concentration of Cr(NO3)3. Our approach provides a reliable way to successfully assemble various other types of particles into cylindrical macrostructures, realizing the shape engineering of nanoscale and microscale structures to macroscopic well-defined architectures for further applications.

Thermosetting supramolecular polymerization of compartmentalized DNA fibers with stereo sequence and length control

Thermosetting supramolecular polymerization of compartmentalized DNA fibers with stereo sequence and length control

Exploiting Self-assembly of Block Copolymers to Fabricate Nanocomposite Thin Films with Controlled Morphology at Nanoscale

As the advantageous properties of nanoparticles (NPs) often emerge only when appropriate coupling and exchange phenomena between the NPs can take place, the control of the inter-particle distance, regular ordering, and location of the nanoparticles onto solid supports is a critical issue. A robust method to control the spatial organization of NPs onto solid supports, based on the use of self-assembling di-block copolymers (BCPs) as structure-guiding material, is reported. Two different polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) BCPs, characterized by a different PS volume fraction, were used as matrices for the fabrication of nanocomposite thin films with cylindrical and lamellar morphologies controlled at the nanoscale. Selective inclusion of surface functionalized gold (Au) and zinc oxide (ZnO) NPs of appropriate size in the PS nanodomains was achieved from dispersions of the BCPs and NPs in a common solvent. The orientation of the BCPs cylinder and lamellar nanodomains in spin-coated thin films was controlled by solvent and thermal annealing protocols, coupled with techniques of surface neutralization.